Breast density and calculated breast cancer risk.

Abstract

1556 Background: Breast density is an independent risk factor for breast cancer; associated with an OR ≥ 4 for very dense breast tissue. Given the prevalence of breast density, the attributable risk may be as high as 33%. The majority of density is determined by heredity however, many factors influence density. Several techniques to quantify density have been described. Here, we evaluate density using the visual analog scale and correlate density with calculated breast cancer risk in a population of women at increased risk for breast cancer. Methods: The High Risk Breast Program database, for women with strong family history, BRCA mutations, high risk pathology or prior chemoradiotherapy for lymphoma, was initiated in 2003 and contains 450+ women. A subset of 37 women ranging in age from 28-63 with a mean lifetime Gail Risk of 22% is the subject of this analysis. Data collected included: mammograms, a medical and dietary history, and BMI. Breast density was interpreted (at baseline and 2 years) from mammograms using a visual analogue scale and reliability was evaluated. Multivariate analyses were performed, using Pearson correlations. Results: Intra-rater variability for density determination at 0 (r = 0.866) and 2 (r = 0.912) year time points was comparable to published studies. Of the variables analyzed, BMI and weight had the most significant influence upon density, with an inversely proportional relationship at both time points (each p = 0.001). Percent density had a significant inversely proportional relationship to short-term (5 year) Gail Risk at both 0 (r = -0.396; p = 0.034) and 2 year (r = -0.359; p = 0.043) time points. Conclusions: Our early results demonstrate the reliability of the visual analogue scale (with high intra-rater variability and correlation with known influences). The negative correlation with risk (also noted by Cuzick et. al 2009) bears further exploration. Breast density may not be an important predictor of risk in high-risk populations. Study accrual is ongoing, and further analysis will clarify this trend. Future studies will need to evaluate the influence of breast density in high and average risk populations. No significant financial relationships to disclose.